Clove bud (Syzygium aromaticum) extract was added at concentrations of 0, 35, 75, and 115 μg/ml to ovine semen extenders in order to investigate the antioxidant activities of clove bud extract and its effects on semen quality parameters after cryopreservation of ram spermatozoa. The basic extender was composed of Tris, egg yolk, and glycerol. Two other extenders were prepared by substitution of egg yolk with either LDL or egg yolk+SDS. The DPPH inhibition test was employed to assess the antioxidant activity of clove bud extract. Results showed that, compared to vitamin E, clove bud extract had a higher antioxidant activity. Better sperm motility and movement characteristics (P<0.05) were observed in the semen diluted with medium containing egg yolk+SDS than in that containing egg yolk and LDL. Progressive motility and movement characteristics of the sperm were significantly improved (P<0.05) by adding 35 and/or 75 μg/ml of clove bud extract to semen extenders. Sperm viability and plasma membrane integrity were also higher (P<0.05) in the semen exposed to medium containing egg yolk+SDS and 75 μg of clove buds extract after cryopreservation processes. Higher levels of clove bud extract, however, had adverse effects on all the sperm quality parameters and significantly reduced (P<0.05) the motility, movement parameters, viability, and plasma membrane integrity of ovine sperm. It was concluded that the clove bud extract had an antioxidant potential that makes it useful for addition to semen extenders and that the best results are obtained with a maximum clove bud extract of 75 μg/ml. Moreover, the combination of egg yolk and a detergent was found to improve sperm quality after the cooling and freeze-thawing processes.
Keywords: Antioxidant; Clove bud; Cryopreservation; Detergent; LDL; Ram; Semen.
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